Roller mill for grinding materials



March 26, 1940. A. SONSTHAGEN ROLLER MILL FOR GRINDING MATERIALS Filed Jan. 8, 1937 Patented Mar. 26, 194\ UNITED STATES ROLLER MILL FOItGRINDIN G MATERIALS Asbjorn Sonsthagen, Snaresbrook, London,

' England Application January 8, 1937, Serial No. 119,709 In Great Britain January 10, 1936 1 Claim.

This invention relates to roller mills for grinding various materials.

When fine grinding is being done it is necessary that the angle of the surfaces at the nip 5 should also be fine.

In order to obtain a fine angle under normal conditions, it is necessary that rollers of large diameter be employed.

The present invention has for its object certain improvements according to which it is possible to obtain very fine angles with rollers of much smaller diameter than are used under the present systems of grinding. This not only presents the advantage that the cost of the smaller rollers is considerably less than the cost of bigger rollers, but the pressure to which the material is subjected at the nip may be adjusted Without reference to the diameter of the rollers. The finer or longer the angle the greater will the pressure be.

According to the present invention the nip is in effect split by inserting a body at or near the nip, the outer or effective surfaces or sides of this body being out of contact with the rollers and being so shaped that a wedge-shaped passage is formed for the material on each side of the body, the said body extending more or less deeply into the nip, the nip splitting body being provided with openings extending therethrough from one side face to the other.

The body just referred to may be placed on one or other side of the nip as may be found most convenient or desirable. A nip split as just described may be employed in conjunction with a device such as forms the subject of the copending application, Serial Number 119,708, which shows a machine for compressing and reducing materials, such as chocolate, paint and the like, into viscid condition, while in film-like condition between pressure surfaces for grinding, mixing or for forcing the materials under high pressure into pressure storage means. 1

In order that the invention may be the better understood, reference is made to the accompanying drawing, in which the single figure is a more or less diagrammatical view showing one arrangement of a device for splitting the nip according to this invention. 7

Referring to the accompanying drawing, in Fig. 1 there is shown means for carrying the invention into effect, such means comprising a thin blade i so placed that it projects downwardly towards the nip b of the rollers a, b, as shown, and its forward end, together with the rollers,

forms a pocket P, at the entrant side of the nip, having restricted entrances P and P The blade I is carried by a suitable holder which, in the example illustrated, is comprised of a pair of plates 4, 5, between which the body of the blade is sandwiched, the whole being held together by the transversely disposed rivets 6. The blade may end upen one side of the centre line 0 of the rollers, or it may extend further into the nip and even project somewhat below the centre line. The shape of the blade holder should be such as will assist the flow of the material towards the nip whereby the said material will be acted upon by the nip under the most favorable conditions.

To this end, as shown upon the drawing, the surface of the holder adjacent the surface of the roller forms an angle with respect thereto, whereby the space between the said surfaces is of gradually decreasing width from the entrant to the discharge point. The angle may be varied as may be found most suitable according to the viscosity of the material being treated.

If the blade is disposed in a vertical or substantially vertical position and above the centre line of the rollers and in a hopper, the material will flow easily towards both sides of the blade. Openings I5 are provided whereby both sides of the body comprised of the plates 4, 5 and the blade I are in communication one with another, without, however, disturbing the flow of the material to the nip.

In the case where the blade is disposed below the centre line of the rollers, as shown in Fig. 2, the direction of rotation of the rollers 2', :i, being in this instance opposite to the direction of rotation of the rollers a, b, there would be provided a housing indicated by 7, the purpose of which would be to hold and guide the material to the grinding nip.

Scrapers, indicated by I3, may be provided where desired.

Whilst throughout the foregoing description it is assumed that a blade such as shown and described will be used, and, as will be readily understood the use of such a blade presents the advantage of cheapness, it may be that under some circumstances a cast or other body will be used, the effective surfaces of which are appropriately shaped to secure the desired results.

I claim:

A roller mill for finely grinding viscous semifluid adhesive materials such as chocolate, paint and the like, said mill including a pair of parallel smooth cylindrical rollers disposed sufliciently closely adjacent to provide a nip for finely grinding such semifluid viscid material; a thin blade-like member having its edge projecting substantially in the direction of movement of the roller surfaces at the nip, said member projecting toward the nip in a plane perpendicular to the plane of the axes of the rollers; the sum of the distances between the margin of the blade-like member and the adjacent rollers approximating but being at least as great as the distance between the rollers at the nip, and said blade being close enough to the rollers to provide grinding passages for said semifluid viscid material; the side faces of said blade-like member being concaved in approximate conformity with the convex face of the rollers respectively to form passages between the blade and rollers; said side faces being so shaped and placed that said faces are close enough to the rollers to provide grinding passages for said material throughout wide angles of the rollers, and so that said passages are progressively narrower in said direction of rotation, thereby to progressively intensify wedging to increase the pressure so that adhesion of the material in the nip is insured to thereby improve the grinding or dispersing action throughout a wide angle as the material moves in said direction; whereby three grinding passages for the viscid material are provided, said member being provided with openings extending therethrough from one side face to the other.

ASBJORN SONSTHAGEN. 

